Kinematics Flashcards
What does kinematics describe?
The motion of bodies regardless of the causes (forces) and the medium
What studies the causes of motion?
Dynamics
What does it mean to describe the motion of a body?
Defining the equations through which it is possible to establish the position of a moving body with respect to a reference system at any time
What is the trajectory?
Line described by a body during motion
Example of known trajectories
Straight line
Parabolic motion
Circular motion
What is a material point=
A body with a defined mass but small in size compared to the pace traveled
Can a material point rotate on itself?
No, only translate
What does the equation of motion express?
The relationship between the space traveled by a material point and the time needed
Does the trajectory tell us anything about the type of motion of the material point?
No
What is instantaneous speed?
The ratio between ^s and ^t
What 2 components can the acceleration vector be decomposed into?
Tangential and perpendicular to the trajectory
What is the tangential component trajectory of an acceleration vector due to?
Variations of the velocity magnitude, not its direction
What does the perpendicular component of an acceleration vector due to?
The curvature of the trajectory (radius of curvature) and from velocity magnitude v
What is the tangential component of the acceleration during uniform motion?
0
What is the velocity during uniform linear motion?
Constant in both magnitude and direction
What is decelerated motion?
Acceleration constant in magnitude but opposite direction with respect to motion
What is the SI unit of frequency?
s^-1
Hz (hertz)
What does static studie?
Conditions of equilibrium of bodies
Where is the center of gravity on a man?
The second saccrual vertebra
Why do quadrupeds have a much more stable balance?
Because the support base is much wider due to the 4 legs
What is a fulcrum?
The thing which a rod rotates around in a lever
What is required for the lever not to rotate around the fulcrum?
The total moment has to be 0
What are the 3 types of levers?
1: fulcrum between effort and resistance
2: resistance between effort and fulcrum
3: effort between the fulcrum and resistance
Examples of type 1 levers
Scissor
Atlanto-occipital joint
Example of type 2 levers
Nutcracker
Standing on your toes
What is the gain of type 2 levers?
Always greater than 1
What is the gain of type 1 levers?
Either greater or less than 1
What is the gain of type 3 levers?
Always less than 1
Example of type 3 levers
Tweezers
The forearm (the elbow is the fulcrum)
Mandible
What is energy defined as?
The ability of a body to perform work
What is kinetic energy?
The energy an object acquires by virtue of its motion
What is potential energy
Energy aquifer by virtue of the position of a body
